Discrimination and xenophobia are endemic conditions to a tribal
animals, such as humans are. From the earliest periods of
city-states, we see discrimination against the residents of other
city-states and peoples of the periphery. The city-states
encouraged this in their propaganda to make their population more
ready to defend the government of those states.
However, particular instances of discrimination, such as
Anti-Black Racism, Anti-Semitism (Judenhass), Anti-Ziganism,
Anti-Catholic hatred, Anti-Protestant hatred, Anti-Muhammadanism,
etc. come as a result of particular political experiences and
historical circumstances. For example, anti-Black Racism developed
from the European need to justify the mass enslavement of Black
peoples prior to shipping them en masse to the Americas. Prior to
this, Blacks were simply a different group of people who were
inferior because they were different than "civilized people", just
as Vikings were. However, in the 15th and 16th centuries literature
developed "explaining" that Blacks were an especially accursed and
more monkey-like people and, therefore, it was not only just to
enslave them, but desirable since they could be "acculturated" by
the European civilizations that would rob them of their lives.